IMPROVING THE PROCESS OF PROCESSING HOLES WITH DRILLS

"One of the urgent problems of mechanical engineering is the processing of holes, which are subject to high requirements for the accuracy of size, shape and location. Most often, hole processing is carried out with the help of rod measuring tools. This is due to their following advantages: relatively high productivity, low costs for pre-production. The quality of the machined holes is determined mainly by the accuracy of the cutting tools, machines and accessories used. The drilling process with existing drills takes place under severe cutting conditions. The magnitude of the front angle on the transverse edge is very unfavorable. For standard spiral drills, the front angle γ on the transverse edge is up to minus 57–60. In view of this, on the transverse edge, instead of cutting, there is a crumpling, squeezing and scraping of metal. When drilling holes with existing drills, the transverse edge of the drill perceives up to 80 % of the axial force, i.e. the resistance to axial feed is created by the contact area of the transverse edge with the workpiece. The specified working conditions of the transverse edge significantly worsen the processing conditions and the quality of the treated hole. To eliminate the transverse edge, a new design of a spiral drill is proposed – a two-vertex spiral drill without a transverse edge, preliminary patent of the Republic of Kazakhstan № 19559. The elimination of the transverse edge on the drill allows you to dramatically reduce the heating and wear of the drill during the cutting process, increase the durability of the drills. The analysis of the results shows that the accuracy of the diametrical dimensions of the holes after processing with two-vertex spiral drills increased by 1, 2 quality compared with spiral drills; roughness decreased by 1, 2 classes. Keywords: spiral drill, jumper, sharpening, durability, accuracy, productivity "